Due to a limitation of a capacity of a cell deployed in a radio network, a congestion may be caused by an excessive access of user equipments (User Equipment, UE), and this scenario is called an access network congestion in a communication system architecture.
In order to alleviate the access network congestion, a network side may take a measure by modifying a quality of service (Quality of Service, QoS) parameter of a bearer of a UE (for example, reducing a maximum bit rate (Maximum Bit Rate, MBR) and a guaranteed bit rate (Guaranteed Bit Rate, GBR) of the bearer), activating a part of bearers, separating a part of users or the like. For illustrative purpose, in the present invention, a UE in this status is called a UE in a congestion and controlled status. When a cell where the UE is located is in a non-congestion status, the network side should remove the measure used to alleviate the congestion so as to restore a normal status of the UE. Therefore, the network side should perceive a congestion status of a cell on an access network side in time. The congestion status may refer to a congestion degree (e.g., high, medium, low, or the like), the non-congestion status or the like. All of congestion statuses in embodiments of the specification refer to this meaning, and in a case of a congestion in an access network side, the access network side should report the congestion status thereof to the network side.
At present, there are two kinds of technical solutions for an access network to report a congestion status, one is to report the congestion status through a control signaling, i.e., in the case of a congestion of an access network side, an access network equipment (an eNodeB or a radio network controller (Radio Network Controller, RNC)) may send a congestion status notification message to a mobility management network element (Mobility Management Entity, MME) or a serving GPRS support node (Serving GPRS Support Node, SGSN), and the mobility management network element notifies a policy and charging control device, for example, a policy and charging rules function (Policy and Charging Rules Function, PCRF) that a bearer modification, a bearer deactivation, or the like may be initiated through a communication network node such as a serving gateway (Serving Gateway, SGW)/packet data network gateway (Packet Data Network Gateway, PGW), a gateway GPRS support node (Gateway GPRS Support Node, GGSN)) or the like. The defect of this solution lie in that the process needs to be added as there is no similar processing process in an existing protocol possibly leading a large influence on the existing protocol.
The other solution is to report the congestion status through a user plane, i.e., when a congestion occurs, a congestion status indication is included in a header of an uplink user plane packet. Then a gateway equipment PGW/a gateway GPRS support node perceives the congestion of the access network, and may notify a policy and charging control equipment to implement a process such as modifying a quality of service of a bearer, deactivating a bearer or the like.
Since a large number of data packets are transmitted in each gateway equipment, if a header of a uplink data packet of a user plane is used to notify the network side of the congestion status of the access network cell, and if each data packet includes information indicating the congestion of the access network cell in a time period before the removal of the congestion, the amount of the data packets used for notifying the congestion status of the access network cell may be huge due to an overlong duration of the congestion, which is inconsistent with currently promoted concepts of energy saving, emission reduction and environmental protection.
Therefore, when congestion occurs, uplink user plane data packets only within a period of time, for example 2s, may be used for notifying the congestion of the access network cell. That is to say, 2s after the occurrence of the congestion of the cell, there is no notification of the congestion of the current network to the network side any more. In addition, according to a specific condition of the congestion of the cell, the congestion status may be divided into multiple grades, such as mild, moderate, severe and the like. The network side may take different measures according to different congestion statuses. Therefore, when the congestion status changes, the access network needs to notify the network side of the current congestion status in time. After the removal of the congestion, the removal of the congestion of the cell may be notified in an uplink user plane data packet, and the network side may also remove a measure taken for alleviating the congestion according to the congestion status of the cell, thereby restoring a normal status of the user. Then, we consider that only within the short period of time (e.g., 2s) when the congestion occurs and when the congestion status changes, the access network equipment notifies the network side of the congestion status thereof through the uplink user plane data packets.
Then, in the prior art, there exists a problem in the following scenario.
A UE resides in a cell covered by an access network, which is congested. After receiving a congestion status notification of the access network, the network side takes a measure such as modifying a QOS of a bearer of the UE and the like. And after the time for the congestion status notification expires, for example, the 2s in the foregoing example expires, then there is no congestion status indication included in the data packets any more. If an access network handover procedure occurs during a movement of the UE, a target access network element may be not congested. After the handover is completed, the target access network element will not include congestion status indication information in the uplink data packets either. Thus, the network side could not perceive that the current UE has performed handover to a non-congested access network cell in time, and could not recover the status of the user in time. This is unreasonable for the user, and the original service level of the user should be restored in time.
To sum up, in the prior art, when the UE performs handover to a non-congested access network cell, the network side may be unable to timely perceive that the UE is currently located in the non-congested access network cell, and can not remove the measure taken for alleviating the congestion, which reduces user experience.